Many applications require that a material be anchored in or to concrete or masonry. For example, anchor bolts are employed in various fields of engineering as strengthening or reinforcing members in rock formations, or concrete or masonry structural bodies. The bolts, which are typically metallic, are inserted into holes in the rock formations, or concrete or masonry structural bodies, are fixed or anchored therein by means of an anchor composition. Typically, the anchor composition cures or hardens (polymerizes) to form a strong bond between the rock formation, or the concrete or masonry structural body and the bolt. In concrete or masonry, anchor bolts are used for reinforcement. Anchor bolts are also used for attaching objects to concrete or masonry. Objects that have been attached to concrete or masonry using anchor bolts include, but are not limited to, electrical conduits, panels, piping and wall sections. Adhesive anchors are preferred over mechanical anchors for anchoring in soft concrete or masonry because adhesive anchors place less stress on the concrete or masonry. As used herein, the term “masonry” shall include, but is not limited to, stone, brick, ceramic tile, cement tile, hollow concrete block and solid concrete block.
A useful anchor composition should be inexpensive, provide for a strong bond between the concrete or masonry and the material to be anchored to the concrete or masonry, be easy to dispense at the location of use and have a long storage shelf life. Some anchor compositions that have been used include compositions based on aromatic vinyl esters, aromatic polyesters and epoxies. These compositions can be expensive or may not provide the desired bond strength between the concrete or masonry and the material that is anchored in or to the concrete or masonry.
An example of the anchor compositions of the prior art is found in Japanese Patent Application Sho59-122762 (“JP '762”). Generally, JP '762 discloses an anchor composition comprising a monomer, a polymer soluble in the monomer, aggregate and a hardening agent. With respect to the monomer component, JP '762 discloses a broad range of compounds which include methacrylate esters. With respect to the polymer component, JP '762 discloses a similarly broad range of compounds which includes methacrylate esters and acrylic acid, and further discloses the use of copolymers. Moreover, JP '762 discloses a composition comprising 70 to 95% by weight of the monomer and 5 to 30% by weight of the polymer.
Notably, however, JP '762 fails to recognize the unexpected and surprising properties of fast cure time and pull out strength realized by the selection of a methacrylate ester monomer and a copolymer of a methacrylic ester and methacrylic acid in the formation of an anchor composition as shown herein. The unexpected and surprising results achieved by this particular combination is shown in certain of the examples set forth below in which significantly shorter cure times and greater pull out strengths are exhibited by the compositions of the present invention as compared to other compositions which fall within the scope of the broad disclosure of JP '762. As a result, the composition of the present invention represent a novel and unobvious advancement over the prior art.